September 19, 1913] 



SCIENCE 



387 



been named in advance the magneton: but 

 I confess that here I have not been shaken 

 out of the conservative view. 



We may express all this as an invasion 

 of number into unsuspected regions. 



Biology may be said to be becoming 

 atomic. It has long had natural units in 

 the shape of cells and nuclei, and some dis- 

 continuity represented by body-boundaries 

 and cell-walls; but now, in its laws of he- 

 redity as studied by Mendel, number and 

 discontinuity are strikingly apparent 

 among the reproductive cells, and the va- 

 rieties of offspring admit of numerical 

 specification and prediction to a surprising 

 extent: while modification by continuous 

 variation, which seemed to be of the essence 

 of Darwinism, gives place to, or at least is 

 accompanied by, mutation, with finite and 

 considerable and in appearance discontinu- 

 ous change. 



So far from nature not making jumps, it 

 becomes doubtful if she does anything else. 

 Her hitherto placid course, more closely 

 examined, seems to look like a kind of 

 steeplechase. 



Yet undoubtedly continuity is the back- 

 bone of evolution, as taught by all biolo- 

 gists — no artificial boundaries or demarca- 

 tions between species — ^a continuous chain 

 of heredity from far below the amceba up to 

 man. Actual continuity of undying germ- 

 plasm, running through all generations, is 

 taught likewise; though a strange discon- 

 tinuity between this persistent element and 

 its successive accessory body-plasms — a dis- 

 continuity which would convert individual 

 organisms into mere temporary accretions 

 or excretions, with no power of influencing 

 or conveying experience to their generating 

 cells — is advocated by one school. 



Discontinuity does not fail to exercise 

 fascination even in pure mathematics. 

 Curves are invented which have no tangent 

 or differential coefficient, curves which con- 



sist of a succession of dots or of twists ; and 

 the theory of commensurable numbers 

 seems to be exerting a dominance over 

 philosophic mathematical thought as well as 

 over physical problems. 



And not only these fairly accepted re- 

 sults are prominent, but some more difficult 

 and unexpected theses in the same direc- 

 tion are being propounded, and the atomic 

 character of energy is advocated. "We had 

 hoped to be honored by the presence of 

 Professor Planck, whose theory of the 

 quantum, or indivisible unit or atom of 

 energy, excites the greatest interest, and by 

 some is thought to hold the field. 



Then again radiation is showing signs of 

 becoming atomic or discontinuous. The 

 corpuscular theory of radiation is by no 

 means so dead as in my youth we thought 

 it was. Some radiation is certainly cor- 

 puscular, and even the etherial kind shows 

 indications, which may be misleading, that 

 it is spotty, or locally concentrated into 

 points, as if the wave-front consisted of de- 

 tached specks or patches; or, as J. J. 

 Thomson says, "the wave-front must be 

 more analogous to bright specks on a dark 

 ground than to a uniformly illuminated 

 surface," thus suggesting that the ether 

 may be fibrous in structure, and that a 

 wave runs along lines of electric force, as 

 the genius of Faraday surmised might be 

 possible, in his "Thoughts on Ray Vibra- 

 tions. ' ' Indeed Newton guessed something 

 of the same kind, I fancy, when he super- 

 posed ether-pulses on his corpuscles. 



Whatever be the truth in this matter, a 

 discussion on radiation, of extreme weight 

 and interest, though likewise of great pro- 

 fundity and technicality, is expected on 

 Friday in Section A. We welcome Pro- 

 fessor Lorentz, Dr. Arrhenius, Professor 

 Langevin, Professor Pringsheim and 

 others, some of whom have been specially 

 invited to England because of the impor- 



